The 3DS is currently at 42.69 million sold. If Pokemon were to have a 30% attachment rate today, it would need to have sold 12.81 million.
Instead, it is at somewhere in the region of 11-11.5 million. As such, it will need to sell 30% of the 3DS, plus 1.3-1.8 million.
Let's have a look at what the situation is likely to be at the end of 2014. The 3DS is likely to sell in the region of 15 million, putting its total at 58 million. Then, Pokemon X/Y will need to have sold 17.4 million, or a total of 7.4 million in 2014. This is incredibly unlikely.
The chances of Pokemon X/Y reaching it earlier than the end of 2014 aren't much greater. If it kept a steady 70,000 for the next 26 weeks (which is incredibly optimistic), it would be at just shy of 13-13.5 million. At the high end (13.5 million) the 3DS would need to be as low as 45 million. That would require the 3DS to only have sold 2.79 million, a 33% drop from 4.176 million in the same period in 2013.
It won't meet it after 2014, either, because it's very unlikely that it will manage to keep at selling 30% of the 3DS after over a year on the market. Even the DS evergreens were far away from that, never managing to get far into the 20%s for a full year.
I think it's safe to say Pokemon X/Y won't reach a 30% attach rate.
